How to Calculate Heat Losses Through Building Walls

My preference is Audel's as the most approachable.

Heat loss and cooling "loss" (actually heat infiltration) are two sides of the same coin, with slightly different individual problems.

Both share one common, unplanned air exchange between inside and outside is #1 enemy. So gaps, cracks, and leaks are the #1 source. Buy caulk.

#2 is insulating properties of materials. Slightly different for cooling, but well explained in any HVAC book.

While any discussion of heat retention focuses on wrapping insulating material around the space, heat rejection may do better with blocking radiant heat intrusion. So frequently one finds radiant barriers used where there is room, they need some space to be effective.

Then start looking at solar mass from a backward point of view. In the winter we try to get solar mass heated by letting sun fall on some slab of concrete. In the summer, you do not want that concrete heated; whether it is through a window in your house or directly outside your house.

So then one has to look at the color of the house, the color of the roof, plantings in the yard.

So there are many aspects, depending on year-round needs, that can be addressed in the structure design, the execution of the design, and the environment in which the design is placed.

I couldn't have said it better myself. This is a simple two-dimensional heat conduction problem, using Fourier's Law.